The calculation of nucleon strangeness form factors from N_f=2+1 clover fermion lattice QCD

TL;DR

This paper computes the nucleon strangeness electromagnetic form factors using N_f=2+1 clover fermion lattice QCD, achieving results consistent with experiments and reducing uncertainties.

Contribution

It introduces improved stochastic methods and increased nucleon sources to enhance signal quality in lattice QCD calculations of strangeness form factors.

Findings

G_M^s(0) = -0.017(25)(07), consistent with experimental data

Significant reduction in error compared to previous studies

Enhanced signal detection through increased nucleon sources

Abstract

We study the strangeness electromagnetic form factors of the nucleon from the N_f=2+1 clover fermion lattice QCD calculation. The disconnected insertions are evaluated using the Z(4) stochastic method, along with unbiased subtractions from the hopping parameter expansion. In addition to increasing the number of Z(4) noises, we find that increasing the number of nucleon sources for each configuration improves the signal significantly. We obtain G_M^s(0) = -0.017(25)(07), where the first error is statistical, and the second is the uncertainties in Q^2 and chiral extrapolations. This is consistent with experimental values, and has an order of magnitude smaller error. We also study the strangeness second moment of the partion distribution function of the nucleon, <x^2>_{s-\bar{s}}.